DEVELOPMENT OF HOUSE HEATING 



133 



The steam system is always closed but the boiler must be 

 provided with a safety valve (Art. 158). 



5. Hot water heating and furnace heating are generally 

 used in small or medium sized buildings where all of the rooms 



FIG. 97. A steam heating plant. The steam trap and reducing valve are 



enlarged. 



to be heated are above the heater or furnace and not far 

 removed from it. They do not give good results when long 

 horizontal pipes must be used. 



